Suboccipitofrontal diameter starts from below the occipital protuberance (below the elevated area of occipital bone)to the middle of the frontal suture. its diameter is 10 cm.it is the engagement diameter of fetus in occipital anterior position.it is the anterior-posterior diameter of the fetal skull.
Occipital anterior position means the back of the head or occipital region of fetal head is attached with the mothers anterior part of the pelvis.
There are two position anterior position ROA( Right occipital anterior position ) and left occipital posterior position (LOA) is normal position for normal delivery.